A case of hypertrophic cardiomyopathy in the transition from childhood to adulthood, which was low risk by the conventional risk assessment model, medium risk by the adult risk prediction model, and high risk by the paediatric risk prediction model, was inserted an implantable cardioverter-defibrillator. Three years post-implantation, the patient was resuscitated with an appropriate discharge of cardioverter-defibrillator.